#include <string>
#include <sstream>
#include <iostream>
#include <stdio.h>
#include <stdlib.h>      /* for malloc, free */
#include <string.h>      /* for memmove */
#include <ctype.h>
#include "stem.h"
using namespace std;

#define LETTER(ch) (isupper(ch) || islower(ch))
#define TRUE 1
#define FALSE 0

/* The main part of the stemming algorithm starts here. b is a buffer
holding a word to be stemmed. The letters are in b[k0], b[k0+1] ...
ending at b[k]. In fact k0 = 0 in this demo program. k is readjusted
downwards as the stemming progresses. Zero termination is not in fact
used in the algorithm.

Note that only lower case sequences are stemmed. Forcing to lower case
should be done before stem(...) is called.
*/

static char * b;       /* buffer for word to be stemmed */
static int k, k0, j;     /* j is a general offset into the string */

						 /* cons(i) is TRUE <=> b[i] is a consonant. */

static int cons(int i)
{
	switch (b[i])
	{
	case 'a': case 'e': case 'i': case 'o': case 'u': return FALSE;
	case 'y': return (i == k0) ? TRUE : !cons(i - 1);
	default: return TRUE;
	}
}

/* m() measures the number of consonant sequences between k0 and j. if c is
a consonant sequence and v a vowel sequence, and <..> indicates arbitrary
presence,

<c><v>       gives 0
<c>vc<v>     gives 1
<c>vcvc<v>   gives 2
<c>vcvcvc<v> gives 3
....
*/

static int m()
{
	int n = 0;
	int i = k0;
	while (TRUE)
	{
		if (i > j) return n;
		if (!cons(i)) break; i++;
	}
	i++;
	while (TRUE)
	{
		while (TRUE)
		{
			if (i > j) return n;
			if (cons(i)) break;
			i++;
		}
		i++;
		n++;
		while (TRUE)
		{
			if (i > j) return n;
			if (!cons(i)) break;
			i++;
		}
		i++;
	}
}

/* vowelinstem() is TRUE <=> k0,...j contains a vowel */

static int vowelinstem()
{
	int i; for (i = k0; i <= j; i++) if (!cons(i)) return TRUE;
	return FALSE;
}

/* doublec(j) is TRUE <=> j,(j-1) contain a double consonant. */

static int doublec(int j)
{
	if (j < k0 + 1) return FALSE;
	if (b[j] != b[j - 1]) return FALSE;
	return cons(j);
}

/* cvc(i) is TRUE <=> i-2,i-1,i has the form consonant - vowel - consonant
and also if the second c is not w,x or y. this is used when trying to
restore an e at the end of a short word. e.g.

cav(e), lov(e), hop(e), crim(e), but
snow, box, tray.

*/

static int cvc(int i)
{
	if (i < k0 + 2 || !cons(i) || cons(i - 1) || !cons(i - 2)) return FALSE;
	{  int ch = b[i];
	if (ch == 'w' || ch == 'x' || ch == 'y') return FALSE;
	}
	return TRUE;
}

/* ends(s) is TRUE <=> k0,...k ends with the string s. */

static int ends(const char * s)
{
	int length = s[0];
	if (s[length] != b[k]) return FALSE; /* tiny speed-up */
	if (length > k - k0 + 1) return FALSE;
	if (memcmp(b + k - length + 1, s + 1, length) != 0) return FALSE;
	j = k - length;
	return TRUE;
}

/* setto(s) sets (j+1),...k to the characters in the string s, readjusting
k. */

static void setto(const char * s)
{
	int length = s[0];
	memmove(b + j + 1, s + 1, length);
	k = j + length;
}

/* r(s) is used further down. */

static void r(const char * s) { if (m() > 0) setto(s); }

/* step1ab() gets rid of plurals and -ed or -ing. e.g.

caresses  ->  caress
ponies    ->  poni
ties      ->  ti
caress    ->  caress
cats      ->  cat

feed      ->  feed
agreed    ->  agree
disabled  ->  disable

matting   ->  mat
mating    ->  mate
meeting   ->  meet
milling   ->  mill
messing   ->  mess

meetings  ->  meet

*/

static void step1ab()
{
	if (b[k] == 's')
	{
		if (ends("\04" "sses")) k -= 2; else
			if (ends("\03" "ies")) setto("\01" "i"); else
				if (b[k - 1] != 's') k--;
	}
	if (ends("\03" "eed")) { if (m() > 0) k--; }
	else
		if ((ends("\02" "ed") || ends("\03" "ing")) && vowelinstem())
		{
			k = j;
			if (ends("\02" "at")) setto("\03" "ate"); else
				if (ends("\02" "bl")) setto("\03" "ble"); else
					if (ends("\02" "iz")) setto("\03" "ize"); else
						if (doublec(k))
						{
							k--;
							{  int ch = b[k];
							if (ch == 'l' || ch == 's' || ch == 'z') k++;
							}
						}
						else if (m() == 1 && cvc(k)) setto("\01" "e");
		}
}

/* step1c() turns terminal y to i when there is another vowel in the stem. */

static void step1c() { if (ends("\01" "y") && vowelinstem()) b[k] = 'i'; }


/* step2() maps double suffices to single ones. so -ization ( = -ize plus
-ation) maps to -ize etc. note that the string before the suffix must give
m() > 0. */

static void step2() {
	switch (b[k - 1])
	{
	case 'a': if (ends("\07" "ational")) { r("\03" "ate"); break; }
			  if (ends("\06" "tional")) { r("\04" "tion"); break; }
			  break;
	case 'c': if (ends("\04" "enci")) { r("\04" "ence"); break; }
			  if (ends("\04" "anci")) { r("\04" "ance"); break; }
			  break;
	case 'e': if (ends("\04" "izer")) { r("\03" "ize"); break; }
			  break;
	case 'l': if (ends("\03" "bli")) { r("\03" "ble"); break; } /*-DEPARTURE-*/

																/* To match the published algorithm, replace this line with
																case 'l': if (ends("\04" "abli")) { r("\04" "able"); break; } */

			  if (ends("\04" "alli")) { r("\02" "al"); break; }
			  if (ends("\05" "entli")) { r("\03" "ent"); break; }
			  if (ends("\03" "eli")) { r("\01" "e"); break; }
			  if (ends("\05" "ousli")) { r("\03" "ous"); break; }
			  break;
	case 'o': if (ends("\07" "ization")) { r("\03" "ize"); break; }
			  if (ends("\05" "ation")) { r("\03" "ate"); break; }
			  if (ends("\04" "ator")) { r("\03" "ate"); break; }
			  break;
	case 's': if (ends("\05" "alism")) { r("\02" "al"); break; }
			  if (ends("\07" "iveness")) { r("\03" "ive"); break; }
			  if (ends("\07" "fulness")) { r("\03" "ful"); break; }
			  if (ends("\07" "ousness")) { r("\03" "ous"); break; }
			  break;
	case 't': if (ends("\05" "aliti")) { r("\02" "al"); break; }
			  if (ends("\05" "iviti")) { r("\03" "ive"); break; }
			  if (ends("\06" "biliti")) { r("\03" "ble"); break; }
			  break;
	case 'g': if (ends("\04" "logi")) { r("\03" "log"); break; } /*-DEPARTURE-*/

																 /* To match the published algorithm, delete this line */

	}
}

/* step3() deals with -ic-, -full, -ness etc. similar strategy to step2. */

static void step3() {
	switch (b[k])
	{
	case 'e': if (ends("\05" "icate")) { r("\02" "ic"); break; }
			  if (ends("\05" "ative")) { r("\00" ""); break; }
			  if (ends("\05" "alize")) { r("\02" "al"); break; }
			  break;
	case 'i': if (ends("\05" "iciti")) { r("\02" "ic"); break; }
			  break;
	case 'l': if (ends("\04" "ical")) { r("\02" "ic"); break; }
			  if (ends("\03" "ful")) { r("\00" ""); break; }
			  break;
	case 's': if (ends("\04" "ness")) { r("\00" ""); break; }
			  break;
	}
}

/* step4() takes off -ant, -ence etc., in context <c>vcvc<v>. */

static void step4()
{
	switch (b[k - 1])
	{
	case 'a': if (ends("\02" "al")) break; return;
	case 'c': if (ends("\04" "ance")) break;
		if (ends("\04" "ence")) break; return;
	case 'e': if (ends("\02" "er")) break; return;
	case 'i': if (ends("\02" "ic")) break; return;
	case 'l': if (ends("\04" "able")) break;
		if (ends("\04" "ible")) break; return;
	case 'n': if (ends("\03" "ant")) break;
		if (ends("\05" "ement")) break;
		if (ends("\04" "ment")) break;
		if (ends("\03" "ent")) break; return;
	case 'o': if (ends("\03" "ion") && j >= k0 && (b[j] == 's' || b[j] == 't')) break;
		if (ends("\02" "ou")) break; return;
		/* takes care of -ous */
	case 's': if (ends("\03" "ism")) break; return;
	case 't': if (ends("\03" "ate")) break;
		if (ends("\03" "iti")) break; return;
	case 'u': if (ends("\03" "ous")) break; return;
	case 'v': if (ends("\03" "ive")) break; return;
	case 'z': if (ends("\03" "ize")) break; return;
	default: return;
	}
	if (m() > 1) k = j;
}

/* step5() removes a final -e if m() > 1, and changes -ll to -l if
m() > 1. */

static void step5()
{
	j = k;
	if (b[k] == 'e')
	{
		int a = m();
		if (a > 1 || (a == 1 && !cvc(k - 1))) k--;
	}
	if (b[k] == 'l' && doublec(k) && m() > 1) k--;
}

/* In stem(p,i,j), p is a char pointer, and the string to be stemmed is from
p[i] to p[j] inclusive. Typically i is zero and j is the offset to the last
character of a string, (p[j+1] == '\0'). The stemmer adjusts the
characters p[i] ... p[j] and returns the new end-point of the string, k.
Stemming never increases word length, so i <= k <= j. To turn the stemmer
into a module, declare 'stem' as extern, and delete the remainder of this
file.
*/

int stem(char * p, int i, int j)
{
	b = p; k = j; k0 = i; /* copy the parameters into statics */
	if (k <= k0 + 1) return k; /*-DEPARTURE-*/

							   /* With this line, strings of length 1 or 2 don't go through the
							   stemming process, although no mention is made of this in the
							   published algorithm. Remove the line to match the published
							   algorithm. */

	step1ab();
	if (k > k0) {
		step1c(); step2(); step3(); step4(); step5();
	}
	return k;
}

string stem(string str) {
	stringstream iss;
	iss << str;
	stringstream oss;
	string tmp;
	while (true)
	{
		char ch = iss.get();
		if (ch == EOF)
			break;
		if (LETTER(ch))
		{
			int i = 0;
			while (true)
			{
				ch = tolower(ch); /* forces lower case */
				tmp.push_back(ch);
				i++;
				ch = iss.get();
				if (!LETTER(ch)) {
					iss.putback(ch);
					break;
				}
			}
			int len = stem((char *)tmp.c_str(), 0, i - 1) + 1;
			oss << tmp.substr(0, len);
		}
		else
			oss << (char)ch;
	}
	return oss.str();
}